1. Field of the Invention
The present invention relates to drill chucks and, more particularly, to a keyless chuck and associated method.
2. Description of Related Art
A standard drill chuck has a body centered on and rotatable about an axis and typically includes a plurality of angled guides extending obliquely to the axis and opening toward the forward end of the chuck. A corresponding plurality of jaws are slidably engaged with the guides, each jaw having a threaded portion. An axially fixed ring is rotatably engaged with the body and is threaded on the inner surface thereof. The threads of the ring mesh with the threaded portions of the jaws such that rotation of the ring about the body displaces the jaws along the guides. Typically, the ring is rotated until the jaws converge toward the axis about the forward end of the chuck, thereby tightening an object or tool between the jaws. A chuck key is then operated between the ring and the body, and used to further tighten (or loosen) the jaws about the tool. However, such a keyed drill chuck requires manual tightening and loosening of the jaws with the chuck key, wherein the chuck key may be easily lost or misplaced, thereby disadvantageously rendering the keyed drill chuck unusable.
Keyless drill chucks represent an improvement over a standard keyed drill chuck in that the need for a chuck key is eliminated. Keyless drill chucks generally include a mechanism configured to engage the ring that cooperates with the jaws to move the jaws in the guides. Such a mechanism may be complex, often requiring multiple cooperating parts. In order to protect the mechanism against, for example, contamination, damage to the chuck or the workpiece, or injury to the operator, the mechanism may be housed in one or more sleeves extending over the mechanism and the body of the chuck. However, heretofore, one of the challenges with keyless drill chucks has been appropriately securing the one or more sleeves in proper position about the mechanism and the body, while allowing the one or more sleeves to have the necessary operability for implementing the function of the mechanism, and while allowing the chuck to be readily assembled and disassembled.
In some instances, external fasteners, such as clips or the like, have been used to secure the one or more sleeves to the body after being inserted thereon. Such a configuration is shown, for example, in U.S. Pat. No. 4,840,387 to McCarthy. However, external fasteners may disadvantageously be prone to accidental disengagement during use of the chuck, the fastener may become unsecured and lost, may cause damage to the workpiece or injury to the operator, or may not be particularly aesthetically pleasing.
In other instances, internal fasteners may be used such as shown, for example, in U.S. Pat. No. 5,573,254 to Huff et al. However, the internal fastener as shown in one embodiment of the Huff '254 reference is assembled toward the forward end of the body before the one or more sleeves are assembled over the body. The fastener is configured to be deformed by the one or more sleeves inserted thereover, wherein teeth or tabs on the fastener are intended to deform and dig into the inner mating surface of a plastic sleeve so as to secure the sleeve in place. However, such deformation-type fasteners may make the chuck difficult to assemble and, if the fastener does not properly secure the sleeve as the sleeve is first installed, the chuck must be disassembled and the fastener replaced or reworked before further attempts can be made to secure the sleeve to the body. Such a deformation-type fastener may also make the chuck difficult to disassemble and, if disassembly is necessary, the fastener will likely have to be replaced before the chuck can be reassembled.
Thus, there exists a need for a keyless chuck having minimal exposed components so as to minimize the risk of damage to a workpiece or the risk of injury to the operator. Minimal exposed components may also make the chuck more aesthetically pleasing. In addition, the components of the chuck should be assembled so as to minimize the possibility of components becoming accidentally disengaged and lost during use of the chuck. Further, such a chuck should desirably be assembled from components that are not required to permanently deform in order to provide the necessary function with respect to the chuck, and to promote ease of assembly and disassembly.